Medical Physics Techniques
Autor: lydiaestelle_x • February 1, 2017 • Coursework • 524 Words (3 Pages) • 665 Views
Unit 20- Medical Physics Techniques
X-rays
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[pic 1]
http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/xtube.html
The evacuated glad tube are where x-rays are made/produced. It starts with the filament being heated by an electrical current. Negatively charged electrons accelerate towards a positive charge, which in this case is the anode (kept cool by circulating oil or water), increasing their kinetic energy. Once the electrons reach this, an amount of this kinetic energy is transformed into x-rays, whilst most ends up as heat. The X-rays then pass through a little whole in the lead shielding.
X-rays have many uses, such as medicine, industry and x-ray crystallography. They are used as a treatment as well as diagnosis in some cancers, making more to reduce the exposure to the patients due to the damage it can cause to the tissue. X-rays absorption appears as white on photographic film, unlike the other darker areas, once they pass through the skin and get absorbed by denser diseased tissue/bone. The x-rays are put through a metal plate before entering the patient, this ensures the tissues don’t heat up or get impaired by the absorption of low-energy protons.
They are also used to inspect casting and welds in industry, much like damages in bone. This means that machines can be inspected without being taken apart.
Studying the structure of crystals is also a use of x-rays, this is called x-ray crystallography. As well as examining crystal structure, this also had led to a reveal in complicated structures, e.g. DNA.
Distinction
X rays are produced by a vacuum tube called an ‘x-ray tube.’ Electrons are emitted into the vacuum and collected by a cathode and an anode, creating a flow of electrons through the tube. A high voltage power source issued to accelerate the electrons. A higher energy of x-ray photon energy when the energy of the particle when it meets the anode is higher, i.e. the wavelength is shorter. Therefore the spectrum is continuous and its low wavelength is inversely proportional to the voltage. [pic 2]
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